High resistivity silicon-on-insulator wafer manufacturing method for reducing substrate loss

ABSTRACT

A multilayer composite structure and a method of preparing a multilayer composite structure are provided. The multilayer composite structure comprises a semiconductor handle substrate having a minimum bulk region resistivity of at least about 500 ohm-cm; a Group IVA nitride layer in contact with the semiconductor handle substrate, the Group IVA nitride layer selected from the group consisting of carbon nitride, silicon carbon nitride, and a combination thereof; a dielectric layer in contact with the Group IVA nitride layer; and a semiconductor device layer in contact with the dielectric layer.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application of U.S. application Ser.No. 14/835,093, filed Aug. 25, 2015, the disclosure of which is herebyincorporated by reference as if set forth in its entirety. U.S.application Ser. No. 14/835,093 claims the benefit of provisionalapplication Ser. No. 62/045,603, filed Sep. 4, 2014, the disclosure ofwhich is hereby incorporated by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of semiconductorwafer manufacture. More specifically, the present invention relates to amethod for producing a semiconductor-on-insulator (e.g.,silicon-on-insulator) structure, and more particularly to a method forproducing a charge trapping layer in the handle wafer of thesemiconductor-on-insulator structure.

BACKGROUND OF THE INVENTION

Semiconductor wafers are generally prepared from a single crystal ingot(e.g., a silicon ingot) which is trimmed and ground to have one or moreflats or notches for proper orientation of the wafer in subsequentprocedures. The ingot is then sliced into individual wafers. Whilereference will be made herein to semiconductor wafers constructed fromsilicon, other materials may be used to prepare semiconductor wafers,such as germanium, silicon carbide, silicon germanium, or galliumarsenide.

Semiconductor wafers (e.g., silicon wafers) may be utilized in thepreparation of composite layer structures. A composite layer structure(e.g., a semiconductor-on-insulator, and more specifically, asilicon-on-insulator (SOI) structure) generally comprises a handle waferor layer, a device layer, and an insulating (i.e., dielectric) film(typically an oxide layer) between the handle layer and the devicelayer. Generally, the device layer is between 0.01 and 20 micrometersthick. In general, composite layer structures, such assilicon-on-insulator (SOI), silicon-on-sapphire (SOS), andsilicon-on-quartz, are produced by placing two wafers in intimatecontact, followed by a thermal treatment to strengthen the bond.

After thermal anneal, the bonded structure undergoes further processingto remove a substantial portion of the donor wafer to achieve layertransfer. For example, wafer thinning techniques, e.g., etching orgrinding, may be used, often referred to as back etch SOI (i.e., BESOI),wherein a silicon wafer is bound to the handle wafer and then slowlyetched away until only a thin layer of silicon on the handle waferremains. See, e.g., U.S. Pat. No. 5,189,500, the disclosure of which isincorporated herein by reference as if set forth in its entirety. Thismethod is time-consuming and costly, wastes one of the substrates andgenerally does not have suitable thickness uniformity for layers thinnerthan a few microns.

Another common method of achieving layer transfer utilizes a hydrogenimplant followed by thermally induced layer splitting. Particles (e.g.,hydrogen atoms or a combination of hydrogen and helium atoms) areimplanted at a specified depth beneath the front surface of the donorwafer. The implanted particles form a cleave plane in the donor wafer atthe specified depth at which they were implanted. The surface of thedonor wafer is cleaned to remove organic compounds deposited on thewafer during the implantation process.

The front surface of the donor wafer is then bonded to a handle wafer toform a bonded wafer through a hydrophilic bonding process. Prior tobonding, the donor wafer and/or handle wafer are activated by exposingthe surfaces of the wafers to plasma containing, for example, oxygen ornitrogen. Exposure to the plasma modifies the structure of the surfacesin a process often referred to as surface activation, which activationprocess renders the surfaces of one or both of the donor water andhandle wafer hydrophilic. The wafers are then pressed together, and abond is formed there between. This bond is relatively weak, and must bestrengthened before further processing can occur.

In some processes, the hydrophilic bond between the donor wafer andhandle wafer (i.e., a bonded wafer) is strengthened by heating orannealing the bonded wafer pair. In some processes, wafer bonding mayoccur at low temperatures, such as between approximately 300° C. and500° C. In some processes, wafer bonding may occur at high temperatures,such as between approximately 800° C. and 1100° C. The elevatedtemperatures cause the formation of covalent bonds between the adjoiningsurfaces of the donor wafer and the handle wafer, thus solidifying thebond between the donor wafer and the handle wafer. Concurrently with theheating or annealing of the bonded wafer, the particles earlierimplanted in the donor wafer weaken the cleave plane.

A portion of the donor wafer is then separated (i.e., cleaved) along thecleave plane from the bonded wafer to form the SOI wafer. Cleaving maybe carried out by placing the bonded wafer in a fixture in whichmechanical force is applied perpendicular to the opposing sides of thebonded wafer in order to pull a portion of the donor wafer apart fromthe bonded wafer. According to some methods, suction cups are utilizedto apply the mechanical force. The separation of the portion of thedonor wafer is initiated by applying a mechanical wedge at the edge ofthe bonded wafer at the cleave plane in order to initiate propagation ofa crack along the cleave plane. The mechanical force applied by thesuction cups then pulls the portion of the donor wafer from the bondedwafer, thus forming an SOI wafer.

According to other methods, the bonded pair may instead be subjected toan elevated temperature over a period of time to separate the portion ofthe donor wafer from the bonded wafer. Exposure to the elevatedtemperature causes initiation and propagation of a crack along thecleave plane, thus separating a portion of the donor wafer. This methodallows for better uniformity of the transferred layer and allows recycleof the donor wafer, but typically requires heating the implanted andbonded pair to temperatures approaching 500° C.

The use of high resistivity semiconductor-on-insulator (e.g.,silicon-on-insulator) wafers for RF related devices such as antennaswitches offers benefits over traditional substrates in terms of costand integration. To reduce parasitic power loss and minimize harmonicdistortion inherent when using conductive substrates for high frequencyapplications it is necessary, but not sufficient, to use substratewafers with a high resistivity. Accordingly, the resistivity of thehandle wafer for an RF device is generally greater than about 500Ohm-cm. With reference now to FIG. 1, a silicon on insulator structure 2comprising a very high resistivity silicon wafer 4, a buried oxide (BOX)layer 6, and a silicon device layer 10. Such a substrate is prone toformation of high conductivity charge inversion or accumulation layers12 at the BOX/handle interface causing generation of free carriers(electrons or holes), which reduce the effective resistivity of thesubstrate and give rise to parasitic power losses and devicenonlinearity when the devices are operated at RF frequencies. Theseinversion/accumulation layers can be due to BOX fixed charge, oxidetrapped charge, interface trapped charge, and even DC bias applied tothe devices themselves.

A method is required therefore to trap the charge in any inducedinversion or accumulation layers so that the high resistivity of thesubstrate is maintained even in the very near surface region. It isknown that charge trapping layers (CTL) between the high resistivityhandle substrates and the buried oxide (BOX) may improve the performanceof RF devices fabricated using SOI wafers. A number of methods have beensuggested to form these high interface trap layers. For example, withreference now to FIG. 2, one of the method of creating asemiconductor-on-insulator 20 (e.g., a silicon-on-insulator, or SOI)with a CTL for RF device applications is based on depositing an undopedpolycrystalline silicon film 28 on a silicon substrate having highresistivity 22 and then forming a stack of oxide 24 and top siliconlayer 26 on it. A polycrystalline silicon layer 28 acts as a highdefectivity layer between the silicon substrate 22 and the buried oxidelayer 24. See FIG. 2, which depicts a polycrystalline silicon film foruse as a charge trapping layer 28 between a high resistivity substrate22 and the buried oxide layer 24 in a silicon-on-insulator structure 20.An alternative method is the implantation of heavy ions to create a nearsurface damage layer. Devices, such as radiofrequency devices, are builtin the top silicon layer 26.

It has been shown in academic studies that the polycrystalline siliconlayer in between of the oxide and substrate improves the deviceisolation, decreases transmission line losses and reduces harmonicdistortions. See, for example: H. S. Gamble, et al. “Low-loss CPW lineson surface stabilized high resistivity silicon,” Microwave Guided WaveLett., 9(10), pp. 395-397, 1999; D. Lederer, R. Lobet and J.-P. Raskin,“Enhanced high resistivity SOI wafers for RF applications,” IEEE Intl.SOI Conf., pp. 46-47, 2004; D. Lederer and J.-P. Raskin, “New substratepassivation method dedicated to high resistivity SOI wafer fabricationwith increased substrate resistivity,” IEEE Electron Device Letters,vol. 26, no. 11, pp. 805-807, 2005; D. Lederer, B. Aspar, C. Laghaé andJ.-P. Raskin, “Performance of RF passive structures and SOI MOSFETstransferred on a passivated HR SOI substrate,” IEEE International SOIConference, pp. 29-30, 2006; and Daniel C. Kerr et al. “Identificationof RF harmonic distortion on Si substrates and its reduction using atrap-rich layer”, Silicon Monolithic Integrated Circuits in RF Systems,2008. SiRF 2008 (IEEE Topical Meeting), pp. 151-154, 2008.

SUMMARY OF THE INVENTION

Among the provisions of the present invention may be noted a multilayerstructure comprising: a semiconductor handle substrate comprising twomajor, generally parallel surfaces, one of which is a front surface ofthe semiconductor handle substrate and the other of which is a backsurface of the semiconductor handle substrate, a circumferential edgejoining the front and back surfaces of the semiconductor handlesubstrate, and a bulk region between the front and back surfaces of thesemiconductor handle substrate, wherein the semiconductor handlesubstrate has a minimum bulk region resistivity of at least about 500ohm-cm; a Group IVA nitride layer in contact with the front surface ofthe semiconductor handle substrate, the Group IVA nitride layer selectedfrom the group consisting of carbon nitride, silicon carbon nitride, anda combination thereof; a dielectric layer in contact with the nitridelayer; and a semiconductor device layer in contact with the dielectriclayer.

The present invention is further directed to a method of forming amultilayer structure, the method comprising: forming a Group IVA nitridelayer on a front surface of a semiconductor handle substrate, whereinthe Group IVA nitride layer is selected from the group consisting ofcarbon nitride, silicon carbon nitride, and a combination thereof andwherein the semiconductor handle substrate comprises two major,generally parallel surfaces, one of which is the front surface of thesemiconductor handle substrate and the other of which is a back surfaceof the semiconductor handle substrate, a circumferential edge joiningthe front and back surfaces of the semiconductor handle substrate, and abulk region between the front and back surfaces of the semiconductorhandle substrate, wherein the semiconductor handle substrate has aminimum bulk region resistivity of at least about 500 ohm-cm; andbonding a front surface of a semiconductor donor substrate to the GroupIVA nitride layer to thereby form a bonded structure, wherein thesemiconductor donor substrate comprising two major, generally parallelsurfaces, one of which is the front surface of the semiconductor donorsubstrate and the other of which is a back surface of the semiconductordonor substrate, a circumferential edge joining the front and backsurfaces of the semiconductor donor substrate, and a central planebetween the front and back surfaces of the semiconductor donorsubstrate, and further wherein the front surface of the semiconductordonor substrate comprises a dielectric layer.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a depiction of a silicon-on-insulator wafer comprising a highresistivity substrate and a buried oxide layer.

FIG. 2 is a depiction of a silicon-on-insulator wafer according to theprior art, the SOI wafer comprising a polysilicon charge trapping layerbetween a high resistivity substrate and a buried oxide layer.

FIG. 3 is a depiction of a high resistivity silicon-on-insulatorcomposite structure with an embedded Group IVA nitride layer.

DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

According to the present invention, a method is provided for preparing asemiconductor-on-insulator composite structure comprising a Group IVAnitride layer on a semiconductor handle substrate, e.g., a singlecrystal semiconductor handle wafer, such as a single crystal siliconwafer. The Group IVA nitride layers are nitrides comprising Group IVAelements, including carbon, silicon, or a combination thereof. Thepresent invention is further directed to a semiconductor handle wafercomprising a Group IVA nitride layer on a surface thereof. The singlecrystal semiconductor handle wafer comprising the Group IVA nitridelayer is useful in the production of a semiconductor-on-insulator (e.g.,silicon-on-insulator) structure. The present invention is thus furtherdirected to a semiconductor-on-insulator composite structure comprisinga semiconductor handle wafer comprising a Group IVA nitride layer. TheGroup IVA nitride layer is located at the interface of the semiconductorhandle wafer and the dielectric layer, e.g., a buried oxide, or BOXlayer, which itself interfaces with a semiconductor device layer.

According to the present invention, the Group IVA nitride layer isformed on a surface of a semiconductor handle substrate, e.g., a singlecrystal silicon wafer, at the region near the oxide interface. Theincorporation of a Group IVA nitride layer at the region near the highresistivity semiconductor wafer-buried oxide interface is advantageoussince defects in the Group IVA nitride layer tend to have deep energylevels. The carriers that are trapped deep in the bandgap require moreenergy to be released, which enhances the effectiveness of a nitridelayer as a charge trapping layer. The Group IVA nitride layer may beselected from among carbon nitride, silicon carbon nitride, and acombination thereof.

The substrates for use in the present invention include a semiconductorhandle substrate, e.g., a single crystal semiconductor handle wafer, anda semiconductor donor substrate, e.g., a single crystal semiconductordonor wafer. FIG. 3 is a depiction of an exemplary, non-limiting highresistivity silicon-on-insulator composite structure with an embeddedwide bandgap layer. The semiconductor device layer 106 in asemiconductor-on-insulator composite structure 100 is derived from thesingle crystal semiconductor donor wafer. The semiconductor device layer106 may be transferred onto the semiconductor handle substrate 102 bywafer thinning techniques such as etching a semiconductor donorsubstrate or by cleaving a semiconductor donor substrate comprising adamage plane. In general, the single crystal semiconductor handle waferand single crystal semiconductor donor wafer comprise two major,generally parallel surfaces. One of the parallel surfaces is a frontsurface of the substrate, and the other parallel surface is a backsurface of the substrate. The substrates comprise a circumferential edgejoining the front and back surfaces, and a central plane between thefront and back surfaces. The substrates additionally comprise animaginary central axis perpendicular to the central plane and a radiallength that extends from the central axis to the circumferential edge.In addition, because semiconductor substrates, e.g., silicon wafers,typically have some total thickness variation (TTV), warp, and bow, themidpoint between every point on the front surface and every point on theback surface may not precisely fall within a plane. As a practicalmatter, however, the TTV, warp, and bow are typically so slight that toa close approximation the midpoints can be said to fall within animaginary central plane which is approximately equidistant between thefront and back surfaces.

Prior to any operation as described herein, the front surface and theback surface of the substrate may be substantially identical. A surfaceis referred to as a “front surface” or a “back surface” merely forconvenience and generally to distinguish the surface upon which theoperations of method of the present invention are performed. In thecontext of the present invention, a “front surface” of a single crystalsemiconductor handle substrate 102, e.g., a single crystal siliconhandle wafer, refers to the major surface of the substrate that becomesan interior surface of the bonded structure. It is upon this frontsurface that the Group IVA nitride layer 108 is formed. Accordingly, a“back surface” of a single crystal semiconductor handle substrate, e.g.,a handle wafer, refers to the major surface that becomes an exteriorsurface of the bonded structure. Similarly, a “front surface” of asingle crystal semiconductor donor substrate, e.g., a single crystalsilicon donor wafer, refers to the major surface of the single crystalsemiconductor donor substrate that becomes an interior surface of thebonded structure, and a “back surface” of a single crystal semiconductordonor substrate, e.g., a single crystal silicon donor wafer, refers tothe major surface that becomes an exterior surface of the bondedstructure. Upon completion of conventional bonding and wafer thinningsteps, the single crystal semiconductor donor substrate forms thesemiconductor device layer 106 of the semiconductor-on-insulator (e.g.,silicon-on-insulator) composite structure.

The single crystal semiconductor handle substrate and the single crystalsemiconductor donor substrate may be single crystal semiconductorwafers. In preferred embodiments, the semiconductor wafers comprise amaterial selected from the group consisting of silicon, silicon carbide,silicon germanium, gallium arsenide, gallium nitride, indium phosphide,indium gallium arsenide, germanium, and combinations thereof. The singlecrystal semiconductor wafers, e.g., the single crystal silicon handlewafer and single crystal silicon donor wafer, of the present inventiontypically have a nominal diameter of at least about 150 mm, at leastabout 200 mm, at least about 300 mm, at least about 450 mm, or more.Wafer thicknesses may vary from about 250 micrometers to about 1500micrometers, suitably within the range of about 500 micrometers to about1000 micrometers.

In particularly preferred embodiments, the single crystal semiconductorwafers comprise single crystal silicon wafers which have been slicedfrom a single crystal ingot grown in accordance with conventionalCzochralski crystal growing methods or float zone growing methods. Suchmethods, as well as standard silicon slicing, lapping, etching, andpolishing techniques are disclosed, for example, in F. Shimura,Semiconductor Silicon Crystal Technology, Academic Press, 1989, andSilicon Chemical Etching, (J. Grabmaier ed.) Springer-Verlag, N.Y., 1982(incorporated herein by reference). Preferably, the wafers are polishedand cleaned by standard methods known to those skilled in the art. See,for example, W. C. O'Mara et al., Handbook of Semiconductor SiliconTechnology, Noyes Publications. If desired, the wafers can be cleaned,for example, in a standard SC1/SC2 solution. In some embodiments, thesingle crystal silicon wafers of the present invention are singlecrystal silicon wafers which have been sliced from a single crystalingot grown in accordance with conventional Czochralski (“Cz”) crystalgrowing methods, typically having a nominal diameter of at least about150 mm, at least about 200 mm, at least about 300 mm, at least about 450mm, or more. Preferably, both the single crystal silicon handle waferand the single crystal silicon donor wafer have mirror-polished frontsurface finishes that are free from surface defects, such as scratches,large particles, etc. Wafer thickness may vary from about 250micrometers to about 1500 micrometers, suitably within the range ofabout 500 micrometers to about 1000 micrometers. In some specificembodiments, the wafer thickness may be about 725 micrometers.

In some embodiments, the single crystal semiconductor wafers, i.e.,handle wafer and donor wafer, comprise interstitial oxygen inconcentrations that are generally achieved by the Czochralski-growthmethod. In some embodiments, the semiconductor wafers comprise oxygen ina concentration between about 4 PPMA and about 18 PPMA. In someembodiments, the semiconductor wafers comprise oxygen in a concentrationbetween about 10 PPMA and about 35 PPMA. Interstitial oxygen may bemeasured according to SEMI MF 1188-1105.

In some embodiments, the semiconductor handle substrate 102, e.g., asingle crystal semiconductor handle substrate, such as a single crystalsilicon handle wafer, has a relatively high minimum bulk resistivity.High resistivity wafers are generally sliced from single crystal ingotsgrown by the Czochralski method or float zone method. Cz-grown siliconwafers may be subjected to a thermal anneal at a temperature rangingfrom about 600° C. to about 1000° C. in order to annihilate thermaldonors caused by oxygen that are incorporated during crystal growth. Insome embodiments, the single crystal semiconductor handle wafer has aminimum bulk resistivity of at least 100 Ohm-cm, such as between about100 Ohm-cm and about 100,000 Ohm-cm, or between about 500 Ohm-cm andabout 100,000 Ohm-cm, or between about 1000 Ohm-cm and about 100,000Ohm-cm, or between about 500 Ohm-cm and about 10,000 Ohm-cm, or betweenabout 750 Ohm-cm and about 10,000 Ohm-cm, between about 1000 Ohm-cm andabout 10,000 Ohm-cm, between about 2000 Ohm-cm and about 10,000 Ohm-cm,between about 3000 Ohm-cm and about 10,000 Ohm-cm, or between about 3000Ohm cm and about 5,000 Ohm-cm. Methods for preparing high resistivitywafers are known in the art, and such high resistivity wafers may beobtained from commercial suppliers, such as SunEdison Semiconductor Ltd.(St. Peters, Mo.; formerly MEMC Electronic Materials, Inc.).

In some embodiments, the front surface of the semiconductor handlesubstrate 102 is cleaned to remove all oxide prior to formation of thewide bandgap layer such that the front surface of the wafer lacks even anative oxide layer. The native oxide may be removed by standard etchingtechniques. In some embodiments, the semiconductor wafer may besubjected to a vapor phase HCl etch process in a horizontal flow singlewafer epitaxial reactor using H₂ as a carrier gas.

In some embodiments, a Group IVA nitride layer 108 is deposited on thefront surface of the semiconductor handle wafer 102. The Group IVAnitride layer 108 may comprise carbon nitride, silicon carbon nitride,or a combination thereof. The Group IVA nitride layer 108 may comprisemultilayers, e.g., two layers, three layers, four layers, or more ofcarbon nitride and silicon carbon nitride. The multilayers may comprisethe same or different materials. The Group IVA nitride layer 108 may becrystalline or amorphous. The Group IVA nitride layer 108 of the presentinvention may be deposited by metalorganic chemical vapor deposition(MOCVD), physical vapor deposition (PVD), chemical vapor deposition(CVD), plasma enhanced chemical vapor deposition (PECVD), or molecularbeam epitaxy (MBE). In some preferred embodiments, the Group IVA nitridelayer 108 of the present invention may be deposited by plasma enhancedchemical vapor deposition (PECVD). The Group IVA nitride layer 108 maybe deposited in a commercially available instrument suitable for PECVD,such as SAMCO's PD-3800 PECVD system. In PECVD, gaseous precursors areinjected into a reactor, and chemical reaction within a plasma betweenthe precursors deposit a layer of atoms onto a semiconductor wafer.Surface reaction of silicon and/or carbon precursors and nitrogenprecursors create conditions for growth. Silicon precursors for PECVDinclude methyl silane, silicon tetrahydride (silane), disilane,trisilane, pentasilane, neopentasilane, tetrasilane, dichlorosilane(SiH₂Cl₂), silicon tetrachloride (SiCl₄), among others. Suitable carbonprecursors for PECVD include methylsilane, methane, ethane, ethylene,among others. Suitable nitrogen precursors suitable for PECVD includephenyl hydrazine, dimethyl hydrazine, tertiary butyl amine, nitrogen andammonia. An exemplary recipe for forming carbon nitride is to injectmethane and nitrogen into the reactive plasma. An exemplary recipe forforming silicon carbon nitride is to inject methane, silane, andnitrogen into the reactive plasma. Nitride layers of carbon nitride orsilicon carbon nitride are particularly advantageous charge trappinglayers since carbon and nitrogen are not electrically active dopant insilicon. Accordingly, high temperature diffusion of carbon or nitrogenfrom the charge trapping layer into the high resistivity substrate orthe device layer will not affect the electrical properties of theselayers.

A PECVD reactor comprises a chamber comprising reactor walls, asusceptor, gas injection units, and temperature control units. The partsof the reactor are made of materials resistant to and non-reactive withthe precursor materials. To prevent overheating, cooling water may beflowing through the channels within the reactor walls. A substrate sitson a susceptor which is at a controlled temperature. The susceptor ismade from a material resistant to the metalorganic compounds used, suchas graphite. For growing nitrides and related materials, a specialcoating on the graphite susceptor may be used to prevent corrosion byammonia (NH₃) gas. Reactive gas is introduced by an inlet that controlsthe ratio of precursor reactants. Chemical reactions are involved in theprocess, which occur after creation of a plasma of the reacting gases.The plasma is generally created by RF (AC) frequency discharge betweentwo electrodes, the space between which is filled with the reactinggases. A Group IVA nitride layer may be deposited to a thickness betweenabout 1 nanometer and about 2000 nanometers, or between about 5nanometers and about 2000 nanometers, or between about 5 nanometers andabout 1000 nanometers, or between about 5 nanometers and about 500nanometers, or between about 100 nanometers and about 500 nanometers,such as between about 200 nanometers and about 500 nanometers by PECVDon a high resistivity semiconductor handle substrate. The growthtemperature may be between about 25° C. and about 1200° C., such asbetween about 100° C. and about 1100° C., preferably between about 100°C. and about 1000° C. The Group IVA nitride layer may be formed underreduced pressure, such as between about 10⁻¹¹ Torr (about 1×10⁻⁹ Pa) toabout 760 Torr (about 101 kPa), or between about 10⁻⁵ Torr (about 0.0013kPa) and about 10 Torr (about 1.33 kPa).

After deposition of the Group IVA nitride layer 108, optionally adielectric layer may be formed on top of the Group IVA nitride layer. Insome embodiments, the dielectric layer comprises an oxide film or anitride film. Suitable dielectric layers may comprise a materialselected from among silicon dioxide, silicon nitride, hafnium oxide,titanium oxide, zirconium oxide, lanthanum oxide, barium oxide, and acombination thereof. In some embodiments, the dielectric layer comprisesan oxide film. Such an oxide film may serve as a bonding surface with anoptionally oxidized semiconductor device substrate and thus may beincorporated into the dielectric layer 104 in the finalsemiconductor-on-insulator composite structure 100. In some embodiments,the dielectric layer comprises silicon dioxide, which may be depositedby means known in the art, such CVD oxide deposition. In someembodiments, the silicon dioxide layer thickness can be between about100 nanometers to about 5 micrometers, such as between about 500nanometers and about 2 micrometers, or between about 700 nanometers andabout 1 micrometer.

After oxide deposition, wafer cleaning is optional. If desired, thewafers can be cleaned, for example, in a standard SC1/SC2 solution.Additionally, the wafers may be subjected to chemical mechanicalpolishing (CMP) to reduce the surface roughness, preferably to the levelof RMS_(2×2 um2) is less than about 50 angstroms, even more preferablyless than about 5 angstroms, wherein root mean squared—

${R_{q} = \sqrt{\frac{1}{n}{\sum\limits_{i = 1}^{n}\; y_{i}^{2}}}},$the roughness profile contains ordered, equally spaced points along thetrace, and y_(i) is the vertical distance from the mean line to the datapoint.

The semiconductor handle substrate 102, e.g. a single crystalsemiconductor handle wafer such as a single crystal silicon handlewafer, prepared according to the method described herein to comprise aGroup IVA nitride layer 108 and, optionally, an oxide film, is nextbonded a semiconductor donor substrate, e.g., a single crystalsemiconductor donor wafer, which is prepared according to conventionallayer transfer methods. That is, the single crystal semiconductor donorwafer may be subjected to standard process steps including oxidation,implant, and post implant cleaning. Accordingly, a semiconductor donorsubstrate, such as a single crystal semiconductor wafer of a materialthat is conventionally used in preparation of multilayer semiconductorstructures, e.g., a single crystal silicon donor wafer, that has beenetched and polished and optionally oxidized, is subjected to ionimplantation to form a damage layer in the donor substrate. In someembodiments, the semiconductor donor substrate comprises a dielectriclayer. Suitable dielectric layers may comprise a material selected fromamong silicon dioxide, silicon nitride, hafnium oxide, titanium oxide,zirconium oxide, lanthanum oxide, barium oxide, and a combinationthereof. In some embodiments, the dielectric layer comprises an oxidelayer having a thickness from about 10 nanometers to about 500nanometers, such as between about 100 nanometers and about 400nanometers.

Ion implantation may be carried out in a commercially availableinstrument, such as an Applied Materials Quantum II. Implanted ionsinclude He, H, H₂, or combinations thereof. Ion implantation is carriedout as a density and duration sufficient to form a damage layer in thesemiconductor donor substrate. Implant density may range from about 10¹²ions/cm² to about 10¹⁶ ions/cm². Implant energies may range from about 1keV to about 3,000 keV. In some embodiments it may be desirable tosubject the single crystal semiconductor donor wafers, e.g., singlecrystal silicon donor wafers, to a clean after the implant. In somepreferred embodiments, the clean could include a Piranha clean followedby a DI water rinse and SC1/SC2 cleans.

In some embodiments, the ion-implanted and optionally cleaned singlecrystal semiconductor donor substrate is subjected to oxygen plasmaand/or nitrogen plasma surface activation. In some embodiments, theoxygen plasma surface activation tool is a commercially available tool,such as those available from EV Group, such as EVG>810LT Low Temp PlasmaActivation System. The ion-implanted and optionally cleaned singlecrystal semiconductor donor wafer is loaded into the chamber. Thechamber is evacuated and backfilled with O₂ to a pressure less thanatmospheric to thereby create the plasma. The single crystalsemiconductor donor wafer is exposed to this plasma for the desiredtime, which may range from about 1 second to about 120 seconds. Oxygenplasma surface oxidation is performed in order to render the frontsurface of the single crystal semiconductor donor substrate hydrophilicand amenable to bonding to a single crystal semiconductor handlesubstrate prepared according to the method described above.

The hydrophilic front surface layer of the single crystal semiconductordonor substrate and the front surface of the single crystalsemiconductor handle substrate, which is optionally oxidized, are nextbrought into intimate contact to thereby form a bonded structure. Sincethe mechanical bond is relatively weak, the bonded structure is furtherannealed to solidify the bond between the donor wafer and the handlewafer. In some embodiments of the present invention, the bondedstructure is annealed at a temperature sufficient to form a thermallyactivated cleave plane in the single crystal semiconductor donorsubstrate. An example of a suitable tool might be a simple Box furnace,such as a Blue M model. In some preferred embodiments, the bondedstructure is annealed at a temperature of from about 200° C. to about350° C., from about 225° C. to about 325° C., preferably about 300° C.Thermal annealing may occur for a duration of from about 0.5 hours toabout 10 hour, preferably a duration of about 2 hours. Thermal annealingwithin these temperatures ranges is sufficient to form a thermallyactivated cleave plane. After the thermal anneal to activate the cleaveplane, the bonded structure may be cleaved.

After the thermal anneal, the bond between the single crystalsemiconductor donor substrate and the single crystal semiconductorhandle substrate is strong enough to initiate layer transfer viacleaving the bonded structure at the cleave plane. Cleaving may occuraccording to techniques known in the art. In some embodiments, thebonded structure may be placed in a conventional cleave station affixedto stationary suction cups on one side and affixed by additional suctioncups on a hinged arm on the other side. A crack is initiated near thesuction cup attachment and the movable arm pivots about the hingecleaving the wafer apart. Cleaving removes a portion of thesemiconductor donor wafer, thereby leaving a semiconductor device layer,preferably a silicon device layer, on the semiconductor-on-insulatorcomposite structure.

After cleaving, the cleaved structure is subjected to a high temperatureanneal in order to further strengthen the bond between the transferreddevice layer and the single crystal semiconductor handle substrate. Anexample of a suitable tool might be a vertical furnace, such as an ASMA400. In some preferred embodiments, the bonded structure is annealed ata temperature of from about 1000° C. to about 1200° C., preferably atabout 1000° C. Thermal annealing may occur for a duration of from about0.5 hours to about 8 hours, preferably a duration of about 4 hours.Thermal annealing within these temperatures ranges is sufficient tostrengthen the bond between the transferred device layer and the singlecrystal semiconductor handle substrate.

After the cleave and high temperature anneal, the bonded structure maybe subjected to a cleaning process designed to remove thin thermal oxideand clean particulates from the surface. In some embodiments, the singlecrystal semiconductor donor wafer may be brought to the desiredthickness and smoothness by subjecting to a vapor phase HCl etch processin a horizontal flow single wafer epitaxial reactor using H₂ as acarrier gas. In some embodiments, an epitaxial layer may be deposited onthe transferred device layer. The finished SOI wafer comprises thesemiconductor handle substrate, the Group IVA nitride layer, thedielectric layer (e.g., buried oxide layer), and the semiconductordevice layer, may then be subjected to end of line metrology inspectionsand cleaned a final time using typical SC1-SC2 process.

According to the present invention, and with reference to FIG. 3, asemiconductor-on-insulator composite structure 100 is obtained with theGroup IVA nitride layer 108 forming an interface with a high resistivitysubstrate 102 and with a dielectric layer 104. The dielectric layer 104is in interface with a semiconductor device layer 106. The dielectriclayer 104 may comprise a buried oxide, or BOX. The Group IVA nitridelayer 108 can be effective for preserving charge trapping efficiency ofthe films during high temperature treatments.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present invention.

Example 1 Silicon-On-Insulator Structure Comprising Group IVA NitrideCharge Trapping Layer

A semiconductor on insulator composite structure 100 of the invention isillustrated in FIG. 3. The SOI structure 100 comprises a highresistivity silicon substrate 102, a buried oxide layer 104, and asilicon device layer 106. At the interface of the high resistivitysilicon substrate 102 and the buried oxide layer 104 is a Group IVAnitride layer 108 comprising one of carbon nitride or silicon carbonnitride layer. The Group IVA nitride layer 108 is deposited in a plasmaenhanced chemical vapor deposition (PECVD) system. After deposition ofthe Group IVA nitride layer 108, the Group IVA nitride layer is cappedby a thick insulator (called box) layer 104. The insulator layer 104 canbe SiO₂ deposited in the same PECVD system or a LPCVD system, or grownin a thermal oxidation furnace. The total thickness of the insulatorlayer 104 is about 7600 angstroms. A conventional donor wafer with about2400 angstroms SiO₂ can then be implanted and bonded to the handlesubstrate 102 with conventional method. The SOI structure 100 is thenheat treated, cleaved, and gone through multiple thermal processes toreach the end of line with standard process flow.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above products and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A method of forming a multilayer structure, themethod comprising: forming a charge trapping layer comprising a GroupIVA nitride layer on a front surface of a silicon wafer handlesubstrate, wherein the charge trapping layer comprising the Group IVAnitride layer comprises a multilayer comprising a carbon nitride layerand a silicon carbon nitride layer, and further wherein the siliconwafer handle substrate comprises two major, generally parallel surfaces,one of which is the front surface of the silicon wafer handle substrateand the other of which is a back surface of the silicon wafer handlesubstrate, a circumferential edge joining the front and back surfaces ofthe silicon wafer handle substrate, and a bulk region between the frontand back surfaces of the silicon wafer handle substrate, wherein thesilicon wafer handle substrate has a minimum bulk region resistivitybetween 2000 Ohm-cm and about 100,000 Ohm-cm; and bonding a donordielectric layer in interfacial contact with a front surface of asemiconductor donor substrate to the Group IVA nitride layer to therebyform a bonded structure, wherein the semiconductor donor substratecomprising two major, generally parallel surfaces, one of which is thefront surface of the semiconductor donor substrate and the other ofwhich is a back surface of the semiconductor donor substrate, acircumferential edge joining the front and back surfaces of thesemiconductor donor substrate, and a central plane between the front andback surfaces of the semiconductor donor substrate, and further whereinthe donor dielectric layer comprises a material selected from the groupconsisting of silicon dioxide, silicon nitride, hafnium oxide, titaniumoxide, zirconium oxide, lanthanum oxide, barium oxide, and a combinationthereof.
 2. The method of claim 1 wherein the silicon wafer handlesubstrate has a bulk resistivity between about 3000 Ohm-cm and about10,000 Ohm-cm.
 3. The method of claim 1 wherein the silicon wafer handlesubstrate has a bulk resistivity between about 3000 Ohm cm and about5,000 Ohm-cm.
 4. The method of claim 1 wherein the carbon nitride layeris formed by chemical vapor deposition or physical vapor deposition froma carbon precursor selected from the group consisting of methane,ethane, ethylene, and any combination thereof and a nitrogen precursorselected from the group consisting of phenyl hydrazine, dimethylhydrazine, tertiary butyl amine, nitrogen, ammonia, and any combinationthereof.
 5. The method of claim 1 wherein the carbon nitride layercomprises a crystalline carbon nitride layer.
 6. The method of claim 1wherein the carbon nitride layer comprises an amorphous carbon nitridelayer.
 7. The method of claim 1 wherein the charge trapping layercomprising the Group IVA nitride layer has an average thickness ofbetween about 1 nanometer and about 2000 nanometers.
 8. The method ofclaim 1 wherein the charge trapping layer comprising the Group IVAnitride layer has an average thickness of between about 200 nanometerand about 500 nanometers.
 9. The method of claim 1 wherein thesemiconductor donor substrate comprises a silicon donor wafer.
 10. Themethod of claim 1 further comprising heating the bonded structure at atemperature and for a duration sufficient to strengthen the bond betweenthe donor dielectric layer in interfacial contact with the front surfaceof the semiconductor donor structure and the charge trapping layercomprising the Group IVA nitride layer in interfacial contact with thefront surface of the silicon wafer handle substrate.
 11. The method ofclaim 10 wherein the semiconductor donor substrate comprises an ionimplanted damage layer.
 12. The method of claim 11 further comprisingmechanically cleaving the bonded structure at the ion implanted damagelayer of the semiconductor donor substrate to thereby prepare a cleavedstructure comprising the silicon wafer handle substrate, the chargetrapping layer comprising the Group IVA nitride layer in contact withthe front surface of the silicon wafer handle substrate, the donordielectric layer in contact with the charge trapping layer comprisingthe Group IVA nitride layer, and a semiconductor device layer in contactwith the donor dielectric layer.
 13. A method of forming a multilayerstructure, the method comprising: forming a charge trapping layercomprising a Group IVA nitride layer on a front surface of a siliconwafer handle substrate, wherein the Group IVA nitride layer comprises acarbon nitride layer and further wherein the silicon wafer handlesubstrate comprises two major, generally parallel surfaces, one of whichis the front surface of the silicon wafer handle substrate and the otherof which is a back surface of the silicon wafer handle substrate, acircumferential edge joining the front and back surfaces of the siliconwafer handle substrate, and a bulk region between the front and backsurfaces of the silicon wafer handle substrate, wherein the siliconwafer handle substrate has a minimum bulk region resistivity between2000 Ohm-cm and about 100,000 Ohm-cm; forming a handle dielectric layercomprising silicon dioxide and having a thickness between about 100nanometers to about 5 micrometers on the charge trapping layercomprising the Group IVA nitride layer; and bonding a donor dielectriclayer in interfacial contact with a front surface of a semiconductordonor substrate to the handle dielectric layer to thereby form a bondedstructure, wherein the semiconductor donor substrate comprising twomajor, generally parallel surfaces, one of which is the front surface ofthe semiconductor donor substrate and the other of which is a backsurface of the semiconductor donor substrate, a circumferential edgejoining the front and back surfaces of the semiconductor donorsubstrate, and a central plane between the front and back surfaces ofthe semiconductor donor substrate, and further wherein the donordielectric layer comprises a material selected from the group consistingof silicon dioxide, silicon nitride, hafnium oxide, titanium oxide,zirconium oxide, lanthanum oxide, barium oxide, and a combinationthereof.
 14. The method of claim 13 wherein the charge trapping layercomprising the Group IVA nitride layer is formed by chemical vapordeposition or physical vapor deposition from a carbon precursor selectedfrom the group consisting of methane, ethane, ethylene, and anycombination thereof and a nitrogen precursor selected from the groupconsisting of phenyl hydrazine, dimethyl hydrazine, tertiary butylamine, nitrogen, ammonia, and any combination thereof.
 15. The method ofclaim 13 wherein the charge trapping layer comprising the Group IVAnitride layer comprises a crystalline carbon nitride layer.
 16. Themethod of claim 13 wherein the charge trapping layer comprising theGroup IVA nitride layer comprises an amorphous carbon nitride layer. 17.The method of claim 13 wherein the charge trapping layer comprising theGroup IVA nitride layer comprises a multilayer comprising the carbonnitride layer and a silicon carbon nitride layer.
 18. The method ofclaim 13 further comprising heating the bonded structure at atemperature and for a duration sufficient to strengthen the bond betweenthe donor dielectric layer in interfacial contact with the front surfaceof the semiconductor donor structure and the handle dielectric layer ininterfacial contact with the charge trapping layer comprising the GroupIVA nitride layer in interfacial contact with the front surface of thesilicon wafer handle substrate.
 19. The method of claim 18 wherein thesemiconductor donor substrate comprises an ion implanted damage layer.20. The method of claim 19 further comprising mechanically cleaving thebonded structure at the ion implanted damage layer of the semiconductordonor substrate to thereby prepare a cleaved structure comprising thesilicon wafer handle substrate, the charge trapping layer comprising theGroup IVA nitride layer in contact with the front surface of the siliconwafer handle substrate, the handle dielectric layer in interfacialcontact with the charge trapping layer comprising the Group IVA nitridelayer, the donor dielectric layer in contact with the handle dielectriclayer, and a semiconductor device layer in contact with the donordielectric layer.
 21. A method of forming a multilayer structure, themethod comprising: forming a charge trapping layer comprising a GroupIVA nitride layer on a front surface of a silicon wafer handlesubstrate, wherein the charge trapping layer comprising the Group IVAnitride layer comprises a multilayer comprising a crystalline siliconcarbon nitride layer and a carbon nitride layer and wherein the siliconwafer handle substrate comprises two major, generally parallel surfaces,one of which is the front surface of the silicon wafer handle substrateand the other of which is a back surface of the silicon wafer handlesubstrate, a circumferential edge joining the front and back surfaces ofthe silicon wafer handle substrate, and a bulk region between the frontand back surfaces of the silicon wafer handle substrate, wherein thesilicon wafer handle substrate has a minimum bulk region resistivitybetween 2000 Ohm-cm and about 100,000 Ohm-cm; and bonding a donordielectric layer in interfacial contact with a front surface of asemiconductor donor substrate to the Group IVA nitride layer to therebyform a bonded structure, wherein the semiconductor donor substratecomprising two major, generally parallel surfaces, one of which is thefront surface of the semiconductor donor substrate and the other ofwhich is a back surface of the semiconductor donor substrate, acircumferential edge joining the front and back surfaces of thesemiconductor donor substrate, and a central plane between the front andback surfaces of the semiconductor donor substrate, and further whereinthe donor dielectric layer comprises a material selected from the groupconsisting of silicon dioxide, silicon nitride, hafnium oxide, titaniumoxide, zirconium oxide, lanthanum oxide, barium oxide, and a combinationthereof.
 22. The method of claim 21 wherein the silicon wafer handlesubstrate has a bulk resistivity between about 3000 Ohm-cm and about10,000 Ohm-cm.
 23. The method of claim 21 wherein the silicon waferhandle substrate has a bulk resistivity between about 3000 Ohm cm andabout 5,000 Ohm-cm.
 24. The method of claim 21 wherein the siliconcarbon nitride is formed by chemical vapor deposition or physical vapordeposition from a silicon precursor selected from the group consistingof methyl silane, silicon tetrahydride (silane), disilane, trisilane,pentasilane, neopentasilane, tetrasilane, dichlorosilane (SiH₂Cl₂),silicon tetrachloride (SiCl₄), and any combination thereof; a carbonprecursor selected from the group consisting of methane, ethane,ethylene, and any combination thereof; and a nitrogen precursor selectedfrom the group consisting of phenyl hydrazine, dimethyl hydrazine,tertiary butyl amine, nitrogen, ammonia, and any combination thereof.25. The method of claim 21 wherein the charge trapping layer comprisingthe Group IVA nitride layer has an average thickness of between about 1nanometer and about 2000 nanometers.
 26. The method of claim 21 whereinthe charge trapping layer comprising the Group IVA nitride layer has anaverage thickness of between about 200 nanometer and about 500nanometers.
 27. The method of claim 21 further comprising forming ahandle dielectric layer comprising silicon dioxide having a thicknessbetween about 100 nanometers to about 5 micrometers on the chargetrapping layer comprising the Group IVA nitride layer before bonding thedonor dielectric layer; and further wherein the handle dielectric layeris bonded to the donor dielectric layer.
 28. The method of claim 21wherein the semiconductor donor substrate comprises a silicon donorwafer.
 29. The method of claim 21 further comprising heating the bondedstructure at a temperature and for a duration sufficient to strengthenthe bond between the donor dielectric layer in interfacial contact withthe front surface of the semiconductor donor structure and the chargetrapping layer comprising the Group IVA nitride layer in interfacialcontact with the front surface of the silicon wafer handle substrate.30. The method of claim 29 wherein the semiconductor donor substratecomprises an ion implanted damage layer.
 31. The method of claim 30further comprising mechanically cleaving the bonded structure at the ionimplanted damage layer of the semiconductor donor substrate to therebyprepare a cleaved structure comprising the silicon wafer handlesubstrate, the charge trapping layer comprising the Group IVA nitridelayer in contact with the front surface of the silicon wafer handlesubstrate, the donor dielectric layer in contact with the Group IVAnitride layer, and a semiconductor device layer in contact with thedonor dielectric layer.
 32. A method of forming a multilayer structure,the method comprising: forming a charge trapping layer comprising aGroup IVA nitride layer on a front surface of a silicon wafer handlesubstrate, wherein the charge trapping layer comprising the Group IVAnitride layer comprises a multilayer comprising an amorphous siliconcarbon nitride layer and a carbon nitride layer and wherein the siliconwafer handle substrate comprises two major, generally parallel surfaces,one of which is the front surface of the silicon wafer handle substrateand the other of which is a back surface of the silicon wafer handlesubstrate, a circumferential edge joining the front and back surfaces ofthe silicon wafer handle substrate, and a bulk region between the frontand back surfaces of the silicon wafer handle substrate, wherein thesilicon wafer handle substrate has a minimum bulk region resistivitybetween 2000 Ohm-cm and about 100,000 Ohm-cm; and bonding a donordielectric layer in interfacial contact with a front surface of asemiconductor donor substrate to the Group IVA nitride layer to therebyform a bonded structure, wherein the semiconductor donor substratecomprising two major, generally parallel surfaces, one of which is thefront surface of the semiconductor donor substrate and the other ofwhich is a back surface of the semiconductor donor substrate, acircumferential edge joining the front and back surfaces of thesemiconductor donor substrate, and a central plane between the front andback surfaces of the semiconductor donor substrate, and further whereinthe donor dielectric layer comprises a material selected from the groupconsisting of silicon dioxide, silicon nitride, hafnium oxide, titaniumoxide, zirconium oxide, lanthanum oxide, barium oxide, and a combinationthereof.